Catadioptric lens optical simulation and unwrapped distortion correction algorithm

Abstract

The panoramic annular optical lens can acquire the information of 360 degrees scene of horizontal plane and condense the image onto a CCD. In this paper a single-lens catadioptric panoramic imaging system is designed by the software ZEMAX to form a panoramic annular image on a CCD which is needed to be unwrapped for easily observation. An improved cubic spline interpolation algorithm is proposed in this paper based on the characters of the annular image for the unwrapping of the image. The new method can preserve the edge and detail of the image much better compared with the nearest interpolation algorithm and bilinear interpolation algorithm. The image already unwrapped still has distortion due to the intrinsic imaging characters of the catadioptric panoramic imaging system. Then the paper shows the evaluation for the distortion of the unwrapped image which derived from the result of image simulation using the optical system mentioned above. A new distortion method is devised when black and white fringe image is used as the input picture for the image simulation to get a distortion correction model which can be applied for the distortion correction of any other unwrapped images. Simulation results show that the panoramic annular optical system can obtain the omnidirectional information factually based on the new unwrapped algorithm and distortion correction algorithm.